Soil stabilizer and soil treated thereby



United States Patent cc Pate, ,452, 1

was then tested for aggregate size by wet sieving and the followingresults were obtained:

z793960 SAMPLE #1 SOIL STABILIZER AND SOIL TREATED THEREBY V 5Percentage by Weight Cornelius H. M; van Bavel Ames Iowa assi or to IowaState College Research Fouiidation, Inc.: Ames, Aggregate 5mm Check 0.2%0.5% Iowa, a corporation of Iowa addltlv additive No Drawing.Application March 11, 1950 M m 97 Serial No. 149,211 7 1(1)]; 7 Claims.(Cl. 106-287) 2.3 ts; 35.5 30.9 22.7

My invention relates to an improved soil stabilizer Mean tD eter n 0 5040.680 0 791 and soil treated thereby. v

Soil stability is a major agronomic. and engineering This sample wasfrom .a continuous corn plot. problem. In the case of agriculturalsoils, lack of sta- I bility leads to erosion, surface-sealing, and thedevelop- SAMPLE #2 ment of poor structure throughout. It has been shownthat erosive soils and soils with poor structure have. less wgg i y andsmaller water-stable aggregates than non-erosive soils A g e S176 111 pwith a good structure. While cropping with grasses and Check 02% legumesincreases considerably the number andsize, of I additive soilaggregates, this prevents simultaneous use of theisoil v p for othercrops and, in addition, is of temporary nature 38:33 I 2.; 1% and doesnot last much more than one season. 1 .5 1

The methods used to improve agricultural soils with 8 2 respect tostability are not always feasible in soilen- Z i 4510 1 40:3 gineering.Frequently soil structures for roads, run- Mean Wei htDmmetermmm 0 1 044ways, mole drains, dams and terraces are not sufiiciently g "i stable towithstand water and fail upon wetting. Yet

the available methods of stabilization are not always Thls 9011 Samplewas from m I a three year effective for such applications. 7 rotation Itis therefore a general object of the present invention SAMPLE 3 toprovide an improved soil characterized by good water stability and anadditive to make the same from ordinary Percentage by Weight soil.Aggregate size in mm.

Further it is an object of the present invention to Check ffig gaigachieve the above ob ects in a manner suitable for use v in engineeringas well as agricultural applications of soil. 6.7 2H 8 Another object ofthe present invention is to provide 5.7 9.0 9.3 a soil characterized byrelatively permanent good water ig gig stability and an additive to makethe same from ordinary 27.0 22.0 17.5 501 21. 7 11.0 14. 4

The novel features which I believe to be characteristic Mean WeightDiameter 111 mm 4588 i 71 1. 754 of my invention are set forth withparticularity in the appended claims. My invention itself, however,together This sample was taken from a corn plot in a three with furtherobjects and advantages thereof, will best year rotation. be understoodby reference to the. following description. The results of the foregoingtests are comparable in In accordance with the present invention, thewater terms of increased stability with the most beneficialagrostabili-ty of soil is increased by the addition thereto of a nomictreatment; namely, many years cropping in small quantity of amethyl-silicon halide, such as a meadow. This will be evident from thefollowing table methylchlorosilane or a methylbromosilane. Suitable 55which shows the results of the sieve testing technique specificcompounds are; monomethylmonochlorosilane applied to a soil similar tothat of sample #3, above: (CI-IaSiI-IaCl), monomethyl dibromosilane(CI-IsSiHBra), dimetliyldichlorosilane ((CH3)2SiCl2), methyltrichl'oro-Percentage by Weight silane (CHaSiCls), and methyltribromosilane(CHsSiBrs). 7 Aggregate Size m I have found that a compound of thisclass, or a mixture Rotation Rotation Continuous of such compounds, addsgreatly to the water stability of Meadlw Bluegrass" the soil to which itis added, whether the stability of the I V soil is measured by thecommon agronomic tests or the g g: Z'if a common engineering tests. 8.5-sle T1410 25.0 p 19.3 7 1:..9 Example ].Treatment of agricultural soil$3 $12 As an example of the treatment of agricultural soil in M an W htter in mm 0.417 0.674 1.783 accordance with the present invention,airdry soil in its natural condition was treated with the vapors of :amix- Addition of approximately 0.5 part by weight of a ture two parts byweight of dimethyldichlorosilane and methyl-silicon halide per parts byweight of soil one part by weight of methyltrichlorosilane at aprestreated as described above provides an unexpectedly sure of from 20to 40 mm. of mercury. The soil sample great reduction in the actualamount of soil loss through Soil loss in tons per year and perPercentage of aggregates above 0.25 mm: size 7 acre not measurable.

From the above table it will be evident that the loss decreases sharplywith greater proportions of particles over 0.25 mm. in size and that theloss becomes insignificant when the percentage exceeds about sixtypercent.

In the case of the first sample mentioned above, the loss in tons peracre, under the same conditions as the above table is approximately 17tons per acre per year,

in the case of untreated soil, 9 tons per acre per year, in 1' the caseof treatment with 0.2 percent of the 2:1 mixture ofdimethyldichlorosilane and methyltrichlorosilane and no appreciable losswhen treated with 0.5 percent of the mixture. In this range the additionof the small quantity of treating material gives a very greatimprovement in the I rate of soil loss, reducing it effectively to zero.

Methylchlorosilanes have an advantage in treating the soil in thattheycan be applied in the vapor state. Their low boiling point of from64 C. to 72 C. permits their application by low pressure or by a streamof hot air and no solvent is necessary. In the case of higher boilingpoint methyl-silicone halides, a solvent or heated air may be used toapply the additive to the soil.

Example 2.Treatment of engineering soil The engineering performance of asoil when Wet is usually measured by its plastic index which is thedifference between the liquid limit moisture percentage and the plasticlimit moisture percentage. The liquid limit moisture percentage is themoisture percentage at which the soil becomes a liquid and flows, underspecified laboratory conditions. The plastic limit moisture percentageis the moisture percentage at which the soil becomes plastic andmoldable under specified laboratory conditions.

In treating the sample soils, a mixture of two parts by weight ofdimethyldichlorosilane and one part by weight of methyltrichlorosilanewas added to the soil as described under Example 1. The plastic indicesof the soil samples were then found to be as follows:

Treatment Reduction of plastic S011 index in Check 0.5% adpercent ditiveSample A 17. 3 14. 0 19 Sample 13... 8. 1 6. 9 15 Sample 0... 15. 8 14.1 11 Sample D 48. 5 39. 8 18 It will be observed that the plastic indexof the soil was substantially reduced.

As further examples of the treatment of soil in accordance with thepresent invention, the soil may be treated withmonomethylmonochlorosilane (CH3SiH2Cl), monomethyldichlorosilane(CHaSiHClz) monomethyldibromosilane CH3SiHBr2) dimethyldichlorosilane((CH3)2SiCl2), methyltrichlorosilane (CHsSiCls) and methyltribromosilane(CH3SiB13). These compounds can best be used in quantities approximating0.5% by weight of the soil although the exact amount necessary toeliminate practically all soil loss varies with the nature of the soiland the specific methyl-silicon halide used.

The term soil as used in the foregoing specification and in the appendedclaims is intended to be understood in its ordinary meaning as referringto the surface layer of the earth, which consists of the witheredmineral and rock fragments of diverse origin, mixed with decaying anddecomposed vegetable and animal matter.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. The method of stabilizing soil against the destructive action ofwater, comprising adding a methyl-silicon halide to soil in its naturalaggregated state, and contacting said soil with said methyl siliconhalide to increase the number and size of the water-stable aggregatestherein.

2. The method of claim 1 in which said methyl-silicon halide is amethylchlorosilane containing from 1 to 3 methyl groups and from 1 to 3chlorine atoms.

3. The method of claim in which said methyl-silicon halide isdimethyldichlorosilane.

4. The method of claim 1 in which said methyl-silicon halide isInononrethyltrichlorosilane.

5. The method of claim 1 in which said methyl-silicon halide ismonomethylmonochlorosil ane.

6. The method of stabilizing soil against the destructive action ofwater, comprising adding a methyl silicon halide .to soil in its naturalaggregated state, and contacting said soil with said methyl-siliconhalide to increase the number and size of the water stable aggregatestherein, said methyl silicon halide being selected from the groupconsisting -of methyl-silicon chlorides and methyl-silicon bromides landbeing added in at least 0.5 parts by weight of said methyl-siliconhalide per each 100 parts of soil contacted.

7. The method of claim 6 in which said methyl-silicon halide is amethylchlorosilane containing from 1 to 3 methyl groups and from 1 to 3chlorine atoms, and said method being further characterized by the factthat said methylchlorosilane is added to said soil in the form ofavapor.

References Cited in the file of this patent UNITED STATES PATENTS2,281,810 Stone May 5, 1942 2,424,853- Salford July 29, 1947 2,474,704Thayer June 28, 1949 2,510,661 Satford June 6, 1950 2,609,305 RoedigerSept. 2, 1952

1. THE METHOD OF STABILIZING SOIL AGAINST THE DESTRUCTIVE ACTION OFWATER, COMPRISING ADDING A METHYL-SILICON HALIDE TO SOIL IN ITS NATURALAGGREGATED STATE, AND CONTACTING SAID SOIL WITH SAID METHYL SILICONHALIDE TO INCREACES THE NUMBER AND SIZE OF THE WATER-STABLE AGGREGATESTHEREIN.